Spasticity is a motor disorder characterised by tight or stiff muscles that may hinder voluntary muscle activities.
It is generally seen in patients with spinal cord injuries (SCI), multiple sclerosis (MS), cerebral palsy (CP) and acquired brain injuries (ABI). Increased tone and spasm reduces the mobility and interferes with the activities of daily living, continence and sleep patterns.
Spasticity may be associated with significant pain or discomfort, skin breakdown, contractures and sleep disorders.
Spasticity is not always detrimental. It provides posture and tone to the limb that can assist with weight bearing, even if the patient cannot able to walk. However, excessive tone may interfere with activities.
Therefore, it is only when the spasticity interferes with the function or puts the patient at risk of hurting himself or herself that it needs to be treated.
The aim of the treatment is to reduce the spasticity in order to recover a range of motion, facilitate movements, decrease energy expenditure and reduces the risk of contractures.
Existing treatment comprises physical therapy, oral medications, injections of phenol or botulinum toxin and surgical intervention.
Baclofen is the most common oral drug, often prescribed for spasticity.
Baclofen is a
- a GABA receptor analogue
- 4-amino-3-(4-chlorophenyl)-butanoic acid.
- It is a muscle relaxant and anti-spasticity drug.
- The oral bioavailability is less due to its limited lipid solubility, resulting in low concentration of the drug in the CSF.
- It is absorbed well in the GIT but does not cross the blood brain barrier.
- Oral dose: 30-60mg
Adverse effects: Baclofen can leads to:
- Excessive weakness
- Mental confusion
- The incidence of adverse effects is ranging from 10% to 75%.
- Adverse effects appear to be its dose-related and may be minimized by initiating the treatment at a low dose and then gradually titrating upwards.
Intrathecal Baclofen: Baclofen administered directly into the spinal CSF
- In order to bypass the oral route to increase its bioavailability, baclofen may be administered intrathecally by infusion directly to the CNS.
- CSF level: 12 to 96 mcg
- Onset on action : 30min to 1hour
- Peak action : -4hrs
- Duration of action: -8hrs
- Renal clearance: 10-85%
Advantages of intrathecal baclofen infusion
- Direct drug delivery to the cerebrospinal fluid (CSF)
- The central side effects of taking oral baclofen, such as confusion and drowsiness are minimized with intrathecal administration.
- Intrathecal administration uses concentrated baclofen of amount less than one hundredth of those which used orally.
- Adjustable or programmable nonstop infusion make it possible to titrate the patient’s doses and to adjust the doses over the hours of the day. For example, the drug doses can be comparatively low to give which the patient’s extensor tone needed for ambulation during daytime and can be increased at night, thereby improving patient’s quality of sleep.
- Reversible procedure (in contrast to surgery).
- Patients who are applicant for the intrathecal baclofen infusion must have no contraindications for the insertion of an intrathecal catheter (e.g., coagulopathy, local or systemic infection, anticoagulant therapy, anatomical abnormality of the spine).
- The level 2 indications supports the effectiveness of the intrathecal baclofen infusion for the short-term duration, lessening the severe spasticity in the patients who are unresponsive or cannot tolerate the oral baclofen.
- The level 3 evidence supports the efficiency of intrathecal baclofen for the longer duration, lessening the severe spasticity in the patients who are unresponsive or cannot tolerate the oral baclofen.
- The level 4 qualitative evidences demonstrate the functional improvement for the patients who are unresponsive or cannot tolerate the oral baclofen.
- The intrathecal baclofen is worthwhile with the cost which may or may not be evaded in the Ontario health system.
- The true functional use remains to be determined yet.
The proper patient selection, meticulous implantation technique, maintenance and the continued vigilance are of paramount importance to reduce the predictable iatrogenic complications and ensure maximum success.
The decision to implant baclofen pump requires careful evaluation of the multifaceted therapeutic measures to ensure the optimal treatment outcomes. When considering a pump, clinicians must consider the comorbidities related to disease and the psychosocial factors such as death and life expectancy.
Thorough explanation of what are the therapy entails and the need for continuous commitment for the therapy titration on part of the patient and the caretaker should be emphasized before proceeding for it.